Plant Tissues

Plants, just like us, are made up of millions of cells. These cells join together to form plant tissues, which have specific roles to play. Different plant tissues work together to create organ systems. This fascinating process is called Plant Tissues.

Examples of Plant Tissues:

Epidermal tissue - This applies to the entire plant. The majority of photosynthesis takes place in the palisade mesophyll tissue, which is a component of the leaf.

Spongy mesophyll tissue - This is located in the leaf as well and has substantial air gaps to provide gas exchange between cells.

Meristem tissue - Tissue can differentiate (transform) into many various types of plant cells, enabling the plant to flourish. It is present at the growing tips of shoots and roots.

Phloem and xylem - They are utilized to move objects around and are two separate tissue types present in blooming plants. Both forms of tissue merge to create "tubes" that connect to every part of the plant, despite the fact that they are fundamentally different from one another.

Phloem

Phloem tubes are responsible for transporting food ingredients, mostly dissolved sugars, from the leaves to other parts of the plant for immediate use or storage. These tubes have tiny openings in their terminal walls that allow cell sap, a liquid composed of water and compounds, to pass through columns of elongated live cells. The process of transporting food ingredients from the leaves down to the roots and from the roots up to the leaves is called translocation. This is how the phloem performs its vital function.

Xylem

Dead cells are connected end to end, with no end walls separating them and a hole running down the middle, to form xylem tubes. They are reinforced by a substance known as lignin.

The function of xylem

Water and mineral ions are transported up the plant by xylem tubes, from the roots to the stem and leaves. The transpiration stream is the term used to describe the flow of water from the roots, through the xylem, and out of the leaves.

Transpiration

A plant loses water through transpiration. The water flowing through a plant from the roots to the leaves is known as the transpiration stream. This is what takes place:

1.       Through the stomata (tiny holes found primarily on the bottom surface of the leaf), water from inside a leaf evaporates and diffuses out of the leaf.

2.       As a result, there is a little scarcity of water in the leaf, and extra water is pulled up through the xylem vessels from the rest of the plant to make up for it.

3.       More water is consequently pulled up from the roots, which results in a continuous flow of water passing through the plant.

There are four main things that effect transpiration:

Light intensity

The rate of transpiration increases with light intensity. As the light level drops, stomata start to close. They don't have to be open to let CO2 in because photosynthesis can't take place in the dark. Little water can escape while the stomata are closed.

Temperature

Transpiration occurs more quickly when the temperature rises. The water molecules have more energy to evaporate and diffuse out of the stomata when it is warm.

Air flow

The rate of transpiration, which is the loss of water vapor from a plant's leaves, increases when there is more airflow around the leaf, such as in a stronger wind. When there is poor airflow around a leaf, water vapor simply surrounds it instead of dispersing. This slows down the process of diffusion because there is a significant concentration of water particles both inside and outside the leaf. However, good airflow helps maintain a low water content in the air surrounding the leaf by sweeping away the water vapor. This allows for rapid diffusion from a region of higher concentration to a region of lower concentration.

Humidity

The rate of transpiration also increases with the dryness of the air surrounding a leaf, similar to how it increases with airflow. When the air is dry, there is less water in it, making it less humid. This creates a greater difference in water concentration between the inside and outside of the leaf, which leads to faster diffusion. On the other hand, when the air is humid, the difference in water concentration between the inside and outside of the leaf is small, which slows down the process of diffusion. Therefore, the dryness of the air greatly affects the rate of transpiration.

Plant Tissues

What are tissues made from?

Cells

What do tissues make up?

An organ system

Give two examples of plant tissues.

Xylem and Phloem

What is transpiration?

The water flowing through a plant from the roots to the leaves is known as the transpiration stream.

What four things affect the transpiration rate?

1.       Humidity

2.       Temperature

3.       Air flow

4.       Light intensity

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